A wave of attacks across Iraq, including a twin car bombing in the country's north, killed at least 20 people, officials have said. 

Wednesday's violence, which struck in and around Baghdad, as well as in Salaheddin and Kirkuk provinces also wounded at least 50 people.

No group immediately claimed responsibility for the attacks, but Sunni fighters have frequently detonated bombs in the disputed northern territory. 

Two people were killed when a suicide bomber set off a truck bomb in Suleiman Bek, while a corpse booby-trapped with explosives killed a policeman in nearby Tuz Khurmatu. Both towns, like Kirkuk, lie in the disputed territory, which stretches from Iraq's border with Iran to its frontier with Syria.

In the adjoining province of Salaheddin, two separate bombings left a policeman and a soldier dead.

And in Baghdad, a car bomb killed four people in a shopping area of the Sunni-majority northern neighbourhood of Saba Abkar, while a policeman was shot dead in another Sunni-dominated district in the south.

Two policemen were also killed by roadside bombs in the capital's northern outskirts.

Sectarian killings

Violence is running at its highest levels since 2006-2007 when Iraq was gripped by a brutal Sunni-Shia sectarian war that killed tens of thousands. 

More than 900 people were killed in Iraq last month, according to figures separately compiled by the United Nations and the Iraqi government, while AFP news agency's tally indicates that more than 4,000 people have been killed so far this year.

On Tuesday, one of the leaders of Iraq's pro-government Sunni armed groups was killed by a suicide bomber in the western Anbar province's capital of Ramadi, one of his men said. 

Mohammed Khamis Abu Risha was touring a checkpoint manned by his fighters in Ramadi when a suicide bomber hugged him, said one of his men. Four of Abu Risha's bodyguards were also killed in the blast, Reuters news agency reported.

Abu Risha was the commander of hundreds of men in the desert province's capital, where security forces and a smaller number of pro-government Sunni tribal fighters have for months been battling tribesmen furious at Prime Minister Nouri Al-Maliki and fighters hailing from the armed group, the Islamic State of Iraq and the Levant (ISIL).

Source: Agencies